Fix DumpRenderTree2 to wait for the WebCore thread to become ready

This is required to make sure that the WebCore thread's message
handlers are ready to receive settings.

Change-Id: I2c4df95e3b7409535b739ada957d93a7e6cd78d6

tests/DumpRenderTree2/src/com/android/dumprendertree2/LayoutTestsExecutor.java

@@ -327,6 +327,13 @@ public class LayoutTestsExecutor extends Activity {
         mCurrentAdditionalTextOutput = null;
 
         mCurrentWebView = createWebViewWithJavascriptInterfaces();
+        // When we create the first WebView, we need to pause to wait for the WebView thread to spin
+        // and up and for it to register its message handlers.
+        if (previousWebView == null) {
+            try {
+                Thread.currentThread().sleep(1000);
+            } catch (Exception e) {}
+        }
         setupWebView(mCurrentWebView);
 
         mEventSender.reset(mCurrentWebView);